Vinylbenzyl thiolesters of carboxylic acids and polymers thereof



e States Pate-uric) j QVINYLBECNIZYL CTHIOLESTERS on cARnoXYLIc ACIDSAND POLYMERS THEREOF "William R. Nummy, Midland, Mich., assignor to TheDow Chemical Company, Midland, Mich., a corporation of Delaware N oDrawing. Filed Apr. 4, 19 57, Ser. No. 650,569

12 Claims. c1. 260-79.7)

This invention concerns certain new vinylbenzyl thiolesters ofcarboxylic acids. It relates more particularly tosuch polymerizableorganic sulfur-containing esters, and polymers thereof and pertains to amethod of making the same.

It is an object of theinvention to provide new poly- J merizable organicsulfur-containing vinylbenzyl thiolesters ofcarboxylic acids. Anotherobject is to prepare new polymers of vinylbenzyl thiolesters of organicthio- .acids. Still another object is to provide a process for "tlierobject is to provide a process for making polymers of vinylbenzylthiolesters of carboxylic thioacids and vinyl making vinylbenzylthiolesters of carboxylic acids. A fur- 3 or vinylidene compounds. Otherand related objects will ester of an organic carbothiolic acid isprepared by react .ing vinylbenzyl chloride with an alkali metal salt'of a appear from the following description of the invention.

According to e the invention the foregoing and related objects areobtained by reacting vinylbenzyl chloride with a carbothiolic acid toform the corresponding vinylbenzyl thiolester and polymerizing themonoethylenically unsaturated sulfur-containing ester, as hereinafterdescribed.

In accordance with the invention a vinylbenzyl thiol- 'carbothiolic acidsuch as thioacetic acid, thiopropionic acid, thiobutyric acid,thioisobutyric acid, thiohexanoic acid, thiolbenzoic acid orthiooctadecanoic acid.

The reactants can be employed in any desired propor-1 tions, but areusually employed in stoichiometric or substantially stoichiometricproportions.

in The reaction is usually carried, out while having the .reactantsdissolved, or suspended, in a substantially anhydrous organic liquidreaction medium such as a lower aliphatic alcohol, e.g. methyl alcohol,ethyl alcohol,

propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl ;aleoho1, oran aromatic hydrocarbon such as benzene, toluene, xylene, ethylbenzene,or mixtures of such organic tcom-pounds, and at temperatures between 25and 125 C., preferably from 40 to 100 C., and at atmospheric pressure orthereabout, although superatmospheric pressures may be used.

; The vinylbenzyl thiolesters have the general formula wherein R is amember of the group consisting of the, phenyl radical alkyl radicalscontaining. from 1 to 17 carbon atoms.

In practice, an alkali metal hydroxide such as sodium hydroxide,potassium hydroxide or lithium hydroxide, is

- dissolved or suspended in finely divided-form in a suitable organicliquid, e.g. methyl alcohol or toluene as reaction medium. Thereaftenacarbothiolic acid, e.g. thioacetic acid, is added in the desiredproportion, suitably in amount chemically equivalent to the alkali metalbysalt of the carbothiolic acid. vinylbenzyl chloride is 2,947,731Patented Aug. 2, 1960 2 added, suitably portionwise or gradually, atabout the rate it is consumed in the reaction while at the same time themixture is agitated or stirred and maintained at reaction temperatureswithin the range of from 25 to 125 C.

Themixture is usually stirred and heated for a short time,

e.g. from 0.5 to 2 hours, after addition of the vinylbenzyl chloride tocomplete the reaction. Alkaliv metal salt 5 usually precipitates duringthe'reaction. The liquid is Yseparated from the salt in usual ways, e.g.by filtering. The filtrate is subjected to distillation to distill andrecover the product, i.e. the vinylbenzyl thiolester.

The vinylbenzyl thiolesters of the invention readily polymerize to formhard viscous products which are soluble in usual organic solvents suchas benzene, toluene, methyl ethyl ketone, ethylene dichloride, etc. Thepolymerization can be carried out in bulk or while having the monomerssuspended in an inert liquid medium, e.g. in.

aqueous emulsion, or brine and in the presence of polymerizationcatalysts such as benzoyl peroxide, lauroyl the correspondingvinylbenzyl thiol.

v7 formula Homopolymers or copolymers of one or more ofthe v ivinylbenzyl thiolesters can be hydrolyzed or alcoholized, e.g. byreaction With an alcoholic solution or mixture of an alkali metalhydroxide and a lower aliphatic alcohol such as methyl alcohol, ethylalcohol or isopropyl alcohol at temperatures between and 120 C., to formpolymeric products containing vinylbenzyl thiol in chemically combinedform. The alkali salts of the polymeric vinylbenzyl thiol aresoluble inaqueous solutions and can be employed as thickening agents for aqueoussolutions or suspensions of finely divided material. Such solublepolymeric products can also be oxidized, e.g. by treatmentwith oxygen oran aqueous solution of Ca(OCl) ,to yield insoluble polymeric productscontaining --SS linkages between the polymer chains.

The following examples illustrate ways in which the principle of theinvention has been applied, but are not I to be construed as limitingits scope.

Example 1 A charge of 1000 cc. of methyl alcohol and 85 grams ofpotassium hydroxide was placed in a glass reaction vessel equipped witha reflux condenser and stirrer. The mixture was stirred and heated to C.A charge of 105 7 grams of thioacetic acid was added slowly over aperiod of one hour. Thereafter, 200 grams of vinylbenzyl chloride (amixture of approximately 30 percent by weight of ortho-vinylbenzylchloride and 70 percent para-vinylbenzyl chloride) was added over aperiod of about one hour while stirring and maintaining the mixture attemperatures between 60 and 64 C. The resulting mixture was stirred andheated at refluxing temperatures for a period of 2 hours, then cooledand filtered to separate the sodium chloride. The liquid filtrate 'Wasdistilled- 'There was obtained 172 grams of vinylbenzyl :Ydi'OXld;thereby forming'the corresponding alkali metal j thiolacetate as ayellow liquid. This product was redisi ed arield i be z l io a e ate b in 5x l at 0.5 millimeter absolute pressure. The product con- 'ketone.preeipitatethe polymer. .polymerized vinylbenzyl thiolacetate as a hardyellow colored solid product.

tained 17.26 percent by weight of sulfur, by analysis.

vinylbenzyl thiolacetate has the formula tween 60 and 64 C. under refluxwhile bubbling nitrogen gas through the same over a period of 2 hours.

Thereafter, the solution was mixed with 1500 cc.of water and 200 cc. oftoluene, then allowed .to stand. The aqueous and organic layers wereseparated. The toluene layer was discarded. The aqueous layer wasacidified with concentrated aqueous hydrochloric acid solution, then wasextracted with two 250 cc. portionsof toluene. The toluene extracts werecombined, dried and heated under reduced pressure to remove the toluene.The residue was distilled. There was obtained 8 =grarns of vinylbenzylthiol as a pale yellow liquid. It was analyzed and foundto contain 21.67percent'by weight of sulfur. Vinylhenzyl thiol has the formula Example 3A charge of 10 grams of the vinylbenzyl .thiolacetate boiling at atemperatureof 95 C. at 0.5 millimeter, preparedin Example 1, was placedin a glass tube, together with.0.01 gram ofalpha,alpha-azobisisobutyronitrile as polymerization catalyst. The tubewas swept out with nitrogen gas, wascooled and sealed. Thetube and itscontents were heated at a temperature of 100 ..C.. f ,or.a period of 4days to polymerize the vinylbenzyl thiolacetate, then cooledto roomtemperature. The tube was broken and the product removed. The productwas a tough leathery solid. It was dissolved -in methyl ethyl Thesolution was pouredinto methyl alcoholto There was obtained 5-grams ofThe polymer contained 16.66;;percent by weight of sulfur.

Example 4 V A mixture of one gram of the polymerized vinylbenzyl.thiolacetateprepared in Example -3, and 50 cc. of a weight percentsolution of potassium hydroxide. dissolved .in..methyl alcohol wasplaced in a glassreaction vessel equipped -with a reflux condenser. The.mixture was heated at refluxing temperatures, about 60.,65 C. for aperiod of minutes while bubbling aslowstreamof nitrogen gas through thesame, then was-cooled to room temperature and was .filtered. Thefiltrate was-diluted Example 5 A charge of 9 grams of styrene and 1 gramof the vinylbenzyl thiolacetate prepared in Example 1, together with0.05 gram of alpha,alpha-azobisisobutyronitrile, was sealed in a glassampoule. The mixture was heated at a temperature of 80 C. for a periodof l9'hours, then cooled. The tube was broken and the polymer removed.

The product was dissolved in methyl ethyl ketone and was f thenprecipitated with methyl alcohol.

There was obtained 8 grams of a hard polymeric product. It was crushedto a granular form and was analyzed. The polymer contained 12.6 percentby weight of chemically combined vinylbenzyl thiolacetate.

Example 6 A charge of 9 grams of methyl acrylate and 1 gram of thevinylbenzyl thiolacetate prepared in Example 1 was sealed in a glasstube, together with 0.05 gram of a20- bisisobutyronitrile, andpolymerized by heating the same at a temperature of C. for a period of 3hours. The polymer was recovered by dissolving the contents of the tubein methyl ethyl ketone, precipitating the polymer with methyl alcohol,separating and drying the same. There was obtained 3 grams of a softrubberlike polymer.

As previously stated the vinylbenzyl thiolesters can be hydrolyzed toform vinylbenzyl thiol or polymerized to form solid products which aresoluble in organic solvents, e.g. toluene, methyl ethyl ketone, ethylenedichloride, etc., or copolymerized with other unsaturated .vinylorvinylidene compounds such as styrene, methyl methacrylate,

methyl :isopropenyl ketone, etc., to .yield resinous .products. Thevinylbenzyl thiolesters are .useful in preparing such other products.The new polymers and copolymers are thermoplastic resins which can beextrudedorimolded inusual ways employing conventional procedures .to'form the general formula wherein R is a member of the groupconsistingobthe .phenyl radical and alkyl radicals containing from ;1.to 17 carbon atoms, which method comprises reactingapproxivmatelyequimolecular proportions of vinylbenzyl. chloride and analkalimetalsalt of a thioacid having tthe general formula:

wherein R has the meaning defined above, at temperatures between 25 andC. while having the reactants dis- ,persed in a substantially anhydrousinert organic Liquid.

2; A method as claimed in claim 1, wherefm thefinert organic liquid is alower aliphatic alcohol.

3. A method of making vinylbenzyl thiolacetate which method comprisesreacting approximately equimolecular proportions of vinylbenzyl chlorideand anjallialimetal thioacetate at temperatures between 25 and e120 -C.while having the reactants dispersed in a'subst'antially anhydrous inertorganic liquid. 7 V i '4. A vinylbenzyl thiolester havin the generalformula:

I! HBC=OH-C 1HlCEr-'S-CR wherein R is a member of the group consistingof the phenyl radical and alkyl radicalscontaining f l 17 .carbon atoms.

5. vinylbenzyl thiolacetate having the empirical formula:

6. A homopolymer of vinylbenzyl thiolacetate.

-7. A copolymer of vinylbenzyl thiolacetate and styrene.

8. A copolymer of vinylbenzyl thiolacetate andmethyl yla e- 9 .A methodof making a polymer containing tvinyl- 5 benzyl thiol chemicallycombined in the polymer molecule, which method comprises hydrolyzing apolymer of a. vinylbenzyl thiolester having the general formula:

wherein R is a member of the group consisting of the phenyl radical andalkyl radicals containing from 1 to 17 carbon atoms, by heating saidpolymer thiolester-containing polymer at temperatures between 50 and 120C. in admixture with an alkali metal hydroxide while having thereactants dispersed in a substantially anhydrous inert organic liquid.

10. A method of making a polymer consisting essentially of polymerizedvinylbenzyl thiol which method comprises hydrolyzing polymerizedvinylbenzyl acetate by heating the polymer at temperatures between 50and 6 120 C. in admixture with an alkali metal hydroxide while havin thereactants dispersed in a substantially anhydrous saturated loweraliphatic alcohol containing from 1 to 4 carbon atoms in the molecule.

11. A polymer comprising vinylbenzyl thiol chemically combined in thepolymer molecule.

12. A' polymer consisting essentially of vinylbenzyl thiol chemicallycombined in the polymer molecule.

References Cited in the file of this patent UNITED STATES PATENTS AllenOct. 21, 1941 Brubaker June 19, 194

OTHER REFERENCES

4. A VINYLBENZYL THIOLESTER HAVING THE GENERAL FORMULA:
 11. A POLYMERCOMPRISING VINYLBENZYL THIOL CHEMICALLY COMBINED IN THE POLYMERMOLECULE.